Thin-film transistor and method for manufacturing same

Abstract

The present invention provides a thin-film transistor in which transistor characteristics such as drain current and threshold voltage are improved, and a method of manufacturing the same. The present invention provides a thin-film transistor provided with a source electrode ( 108 ), a drain electrode ( 109 ), a semiconductor layer ( 105 ), a gate electrode ( 103 ), and an insulating layer ( 104 ); wherein the semiconductor layer ( 105 ) contains a composite metal oxide obtained by adding to a first metal oxide an oxide having an oxygen dissociation energy that is at least 200 kJ/mol greater than the oxygen dissociation energy of the first metal oxide, whereby the amount of oxygen vacancy is controlled; and the insulating layer ( 104 ) is provided with an SiO 2 layer, a high-permittivity first layer, and a high-permittivity second layer, whereby the dipoles generated at the boundary between the SiO 2 layer and the high-permittivity layers are used to control the threshold voltage.

The invention claimed is: 
     
       1. A thin-film transistor comprising:
 a source electrode and a drain electrode; 
 a semiconductor layer provided in contact with the source electrode and the drain electrode; 
 a gate electrode provided corresponding to a channel between the source electrode and the drain electrode; and 
 an insulating layer provided between the gate electrode and the semiconductor layer, 
 wherein the semiconductor layer is a composite metal oxide obtained by adding, to a first metal oxide capable of generating an electron carrier by introducing oxygen vacancy, an oxide having oxygen dissociation energy that is greater than oxygen dissociation energy of the first metal oxide by at least 200 kJ/mol, 
 wherein the semiconductor layer uniformly comprises an additional oxide having oxygen dissociation energy that is smaller than the oxygen dissociation energy of the first metal oxide in an amount smaller than an additive amount of the oxide. 
 
     
     
       2. The thin-film transistor according to  claim 1 , wherein the oxygen dissociation energy of the oxide is greater than the oxygen dissociation energy of the first metal oxide by at least 255 kJ/mol. 
     
     
       3. The thin-film transistor according to  claim 1 , wherein the first metal oxide contains at least one selected from the group consisting of indium, gallium, zinc and tin. 
     
     
       4. The thin-film transistor according to  claim 1 , wherein the oxide contains a second metal oxide composed of an oxide of at least one metal selected from the group consisting of zirconium (Zr) and praseodymium (Pr). 
     
     
       5. The thin-film transistor according to  claim 2 , wherein the oxide contains a second metal oxide composed of an oxide of at least one metal selected from the group consisting of silicon (Si), tantalum (Ta), lanthanum (La) and hafnium (Hf). 
     
     
       6. The thin-film transistor according to  claim 1 , wherein a content of the oxide in the composite metal oxide is greater than 0 and not more than 50 wt %. 
     
     
       7. The thin-film transistor according to  claim 1 , wherein a content of the oxide is greater than 0 and not more than 5 wt %. 
     
     
       8. The thin-film transistor according to  claim 1 , wherein the oxide contains at least one element selected from the group consisting of boron (B) and carbon (C). 
     
     
       9. The thin-film transistor according to  claim 8 , wherein a content of boron (B) and carbon (C) contained in the composite metal oxide is greater than 0 and not more than 10 wt %. 
     
     
       10. A method of manufacturing the thin-film transistor according to  claim 1 , wherein the semiconductor layer is formed at 10° C. or more and 600° C. or less. 
     
     
       11. The method of manufacturing the thin-film transistor according to  claim 10 , wherein the semiconductor layer is formed at 10° C. or more and 200° C. or less. 
     
     
       12. The thin-film transistor according to  claim 1 , wherein a content of the additional oxide is greater than 0 and not more than 10 wt %. 
     
     
       13. The thin-film transistor according to  claim 1 , wherein the additional oxide is at least one oxide selected from the group consisting of lead oxide, palladium oxide, platinum oxide, sulfur oxide, antimony oxide, strontium oxide and ytterbium oxide. 
     
     
       14. A method of manufacturing the thin film transistor according to  claim 1 , wherein the semiconductor layer is formed at 10° C. or more and 600° C. or less.